Im not sure if I can give great advice....but it sounds like he stopped talking to you abruptly? Maybe, something randomly came up? maybe his partner found out something? (Sorry if I didnt follow your post correctly!)
Maybe be more direct with him about wanting to be friends? (sorry again if im giving stupid advice )
Sounds like something happened that made him change suddenly.

Hope this reply wasnt a complete fail

but im sending u lots of hugs full of support Switch